(1) Field of the Invention
The present invention relates to a cassette loading device for loading a magnetic tape cassette selected from multiple types of magnetic tape cassettes different in outside dimensions from one another.
(2) Description of the Prior Art
In recent years, a variety of magnetic recording/reproducing apparatuses (to be referred to hereinbelow as VTR) of various standards (i.e., magnetic recording methods) have been developed into products, and various VTRs based on different standards tend to compete for market share. For this reason, various kinds of magnetic tape cassettes (to be referred to hereinbelow as cassette) corresponding to different standards or various kinds of cassettes based on the same standard but different in cassette size (outside diameter, reel distance) are put onto the market. As a result, it is necessary for users to pay attention to the interchangeability between cassettes.
For this reason, the market demands a general-purpose VTR which can deal with different standards and different cassette sizes. As a VTR having such general-purpose characteristics, a compatible VTR which can perform recording and reproduction for two types of cassettes on the same standard but different in size, namely, the standard cassette (to be called L-cassette) and the compact cassette (to be called S-cassette), has been developed.
Referring next to the drawings, an example of the conventional compatible VTR will be described.
FIGS. 1A and 1B are plan views showing a conventional cassette loading device 100 incorporated in the compatible VTR; FIG. 2 is a front view of FIG. 1; and FIGS. 3A, 3B, 4A, 4B and 5 are perspective views showing essential parts.
Cassette loading device 100 has a cassette holder 101, which is integrally formed of a top portion 102, left and right side portions 103, and L-cassette guiding pieces 104 for guiding the undersurface of L-cassette LC. L-cassette guiding piece 104 has an integrally formed S-cassette guiding piece 105 at its distal end. L-cassette guiding piece 104 has a stopper piece 104a which has been formed upright to bear the front part, with respect to the cassette's direction of movement, of L-cassette LC. Further, S-cassette guiding piece 105 has a stopper piece 105a which has been formed upright to bear the front part, with respect to the cassette's direction of movement, of S-cassette SC.
Each side portion 103 has 1st through 3rd slider axles 106A, 106B and 106C press fitted. Leaf springs 107 and 108 for pressing L-cassette and S-cassette, respectively are press fitted in top portion 102. In the mode shown in FIG. 3B, an engaging boss 106D is provided on only the side portion 103 located on the right side in the figure.
A mech-chassis 109 which supports cassette loading device 100, has a pair of right and left frames 110A and 110B standing upright parallel to each other. Each frame 110A and 110B has integrally formed, inwardly bent flanges 110a on the upper edge thereof. A top plate 111 supported by these flanges 110a, is provided between frames 110A and 110B. Pivotally supported between frames 110A and 110B is a cassette port door 112 for opening and closing the port of cassette holder 101. Cassette port door 112 is biased toward the closed direction by an unillustrated door shutting spring.
Frames 110A and 110B each have a 1st L-shaped guide slot 113a engaged with and guiding 1st slider axle 106A of cassette holder 101, and a 2nd L-shaped guide slot 113b engaged with and guiding 2nd slider axle 106B, whereby cassette holder 101 is supported so as to be able to slide along guide slots 113a and 113b. Further, frames 110A and 110B each have a rib-formed guide slot 113c which is engaged with 3rd slider axle 106C to guide the downward movement of cassette holder 101 when it moves downwards (to be described later).
Drive arms 114A and 114B are pivoted on the inner sides of respective frames 110A and 110B so that they are free to rock back and forth. Drive arms 114A and 114B each have a semicircular gear 114a formed coaxially with the support axle thereof. Rotationally supported between left and right frames 110A and 110B is a link shaft 115. This link shaft 115 has timing gears 116, 116 attached at both ends in phase. Timing gears 116, 116 are in mesh with semicircular gears 114a of drive arms 114A and 114B, respectively, so that both drive arms 114A and 114B will sway integrally.
Drive arms 114A and 114B have respective slots 114b, 114b, which extend along the length thereof. This slot 114b is engaged with 1st slider axle 106A which also fits through 1st guide slot 113a. Left drive arm 114B has another semicircular gear 114c which is formed coaxially with the support axle of drive arm 114B. Drive arms 114A and 114B each have a cassette pressing spring 114d which urges 1st slider axle 106A engaging slot 114b, in such a direction as to press the distal end of drive arm 114A or 114B toward the chassis interior (in the clockwise direction in FIGS. 4A and 4B, and in the counterclockwise direction in FIG. 5).
The outer side of left frame 110B has 4th through 6th slider axles 117A, 117B and 117C press fitted thereon. A double-acting plate 118 is provided on the outer side of left frame 110B. Double-acting plate 118 has guide slots 118a, 118b and 118c which are engaged with 4th through 6th slider axles 117A to 117C, respectively, so that double-acting plate 118 will be able to move back and forth relative to frame 110B in the cassette's direction of movement. Double-acting plate 118 has a rack gear 118d meshed with semicircular gear 114c of drive arm 114B so that double-acting plate 118 will move linearly in the cassette's direction of insertion as drive arm 114B moves swayingly.
Provided on the outer side of double-acting plate 118 is a driving plate 119, which has guide slots 119a, 119b and 119c engaged with 4th through 6th slider axles 117A to 117C, respectively. By this arrangement, driving plate 119 will be able to move back and fourth relative to frame 110B in the cassette's direction of movement.
A double-acting spring 120, a tension spring is provided between double-acting plate 118 and driving plate 119 at their inner ends thereof. Formed on the near end of driving plate 119 is an abutment piece 119d which is bent toward double-acting plate 118 so that it will abut double-acting plate 118. Driving plate 119 has a rack gear 119e which, similarly to rack gear 118d, is in mesh with semicircular gear 114c and another rack gear 119f which receives the driving force from an unillustrated driver motor for loading.
Rack gear 118d is formed with such a length as to be in mesh with semicircular gear 114c from the beginning of the rocking movement of drive arm 114B to the end. Rack gear 119e is formed with such a length that it will not be in mesh at the beginning of the rocking movement of drive arm 114B but will become engaged with the other semicircular gear 114c of the drive arm 114B in the course of rocking movement of the arm to the end.
In the mode shown in FIG. 1B, mech-chassis 109 has a light emitter 121. Provided on the inner side of frame 110A positioned on the right side in FIG. 1B are a light-receiving sensor 122 that receives the sensor light from light emitter 121 and a shutter 123 as shown in FIG. 4B. Shutter 123 is provided so as to move up and down along the inner side of frame 110A and is urged upward by means of a spring 124. Shutter 123 has a slanting surface 123a in the upper part thereof which is engaged with engaging boss 106D of cassette holder 101. Further, shutter 123 is formed with an opening 123b which allows completion of the optical path from light emitter 121 to light-receiving sensor 122 only when engaging boss 106D becomes engaged with the shutter forcibly moving it downwards.
The sensing device consisting of light emitter 121 and light-receiving sensor 122 detects the timing of starting the cassette in-pulling operation (to be described next), and in addition, performs BOT detection (detection of the beginning of taking up the magnetic tape accommodated in cassette LC or SC) and EOT detection (detection of the end of taking up the magnetic tape accommodated in cassette LC or SC). Due to the tape winding direction of the cassette, the sensing device provided on the right of the frame in the figure is adapted to detect BOT, whereas the sensing device on the left of the frame is adapted to detects EOT.
Referring next to FIGS. 6A-6F, the loading operation of an L-cassette LC will be described. First, as shown in FIGS. 6A and 6C, an L-cassette LC is inserted from an unillustrated inserting port so that it is placed on L-cassette guiding piece 104 of cassette holder 101. A further insertion of the L-cassette LC into the chassis interior makes it abut stopper piece 104a, on its inner side edge with respect to the moving direction of LC-cassette LC. In this condition, the L-cassette LC is pressed against L-cassette guiding piece 104 from above by leaf springs 107, so that it will be stably held inside cassette holder 101.
When the L-cassette LC is further pushed in, the L-cassette LC presses stopper piece 104a so that cassette holder 101 slightly moves inward. At this moment, 1st and 2nd slider axles 106A and 106B move whilst being guided along respective 1st and 2nd guide slots 113a and 113b. The distal ends of drive arms 114A and 114B whose slots 114b are engaged with 1st and 2nd slider axles 106A and 106B, move swayingly toward the chassis interior (in the clockwise direction in FIGS. 4A, 6C to 6F, and in the counterclockwise direction in FIG. 5). Then, double-acting plate 118 meshed with semicircular gear 114c formed in left drive arm 114B slightly moves toward the chassis interior.
As shown in FIG. 6D, when double-acting plate 118 has moved slightly toward the chassis interior, engaging boss 106D formed in cassette holder 101 becomes engaged with slanting surface 123a of shutter 123 so as to forcibly move shutter 123 downward opposing the force of spring 124. As a result, opening 123b of shutter 123 moves into the optical path between light emitter 121 and light-receiving sensor 122 so that it allows light-receiving sensor 122 to receive the sensor light from light emitter 121. This activates an unillustrated motor whose driving force is transmitted to rack gear 119f. As a result, driving plate 119 moves toward the chassis interior. When it has moved to a position where abutment piece 119d abuts double-acting plate 118, double-acting plate 118 together with driving plate 119 begins to move toward the chassis interior.
When double-acting plate 118 has been forcibly shifted toward the chassis interior by driving plate 119, the arm end of drive arm 114B meshed with rack gear 118d swayingly moves toward the chassis interior (in the clockwise direction in FIGS. 4A, 6C to 6F, and in the counterclockwise direction in FIG. 5) while driving arm 114A also swayingly moves in the same direction through timing gear 116, link shaft 115 and timing gear 116. Then, 1st slider axles 106A engaging slots 114b of drive arms 114A and 114B move toward the chassis interior, and this causes cassette holder 101 to move together with the L-cassette LC toward the chassis interior.
In this way, as cassette holder 101 continues to move toward the chassis interior, 1st and 2nd slider axles 106A and 106B, as also shown in FIG. 6E, will reach the vertically slotted portions of 1st and 2nd guide slots 113a and 113b, and 3rd slider axle 106C will become engaged with rib-formed guide slot 113c.
Before 1st and 2nd slider axles 106A and 106B reach the vertically slotted portions of 1st and 2nd guide slots 113a and 113b, an unillustrated cassette size detecting lever provided on mech-chassis 109 detects the inserted cassette as to be an L-cassette LC, to thereby drive an unillustrated reel table shifting mechanism. In this way, unillustrated reel tables are adjusted so that the distance between the reel tables will match the reel distance of L-cassette LC.
When driving plate 119 is further driven toward the chassis interior by an unillustrated motor, drive arms 114A and 114B sways more. Then, 1st and 2nd slider axles 106A and 106B move downwards along the vertically slotted portions of 1st and 2nd guide slots 113a and 113b, and 3rd slider axles 106C go down along rib-formed guide slots 113c. Consequently, cassette holder 101 moves downwards together with the L-cassette LC.
When cassette holder 101 has moved down to its terminal position, the L-cassette LC is placed on four cassette stays 125 (see FIG. 6F) planted on mech-chassis 109. In this condition, cassette holder 101 is pressed downwards by means of cassette pressing springs 114d provided for drive arms 114A and 114B. Therefore, the L-cassette LC becomes pressed in contact with cassette stays 125 with its bottom slightly spaced away from L-cassette guiding piece 104.
Thus, the loading operation of L-cassette LC is completed. The ejecting operation of L-cassette LC is effected in the reverse order of the aforementioned loading operation.
Next, the loading operation of an S-cassette SC will be described. First, as shown in FIGS. 7A and 7C, the S-cassette SC is inserted from an unillustrated inserting port so that it is placed on S-cassette guiding piece 105 of cassette holder 101. A further insertion of the S-cassette SC into the chassis interior makes it abut stopper piece 105a, on its inner side edge with respect to the moving direction of SC-cassette SC. In this condition, the S-cassette SC is pressed against S-cassette guiding piece 105 from above by leaf springs 108, so that it will be stably held inside cassette holder 101.
When the S-cassette SC is further pushed in, the S-cassette SC presses stopper piece 105a so that cassette holder 101 slightly moves inward. As a result, 1st and 2nd slider axles 106A and 106B move whilst being guided along respective 1st and 2nd guide slots 113a and 113b. The distal ends of drive arms 114A and 114B whose slots 114b are engaged with 1st and 2nd slider axles 106A and 106B, swayingly move toward the chassis interior (in the clockwise direction in FIGS. 4A, 7C and 7D, and in the counterclockwise direction in FIG. 5). As a result, double-acting plate 118 meshed with semicircular gear 114c formed in left drive arm 114B slightly moves toward the chassis interior.
As shown in FIG. 7D, when double-acting plate 118 has moved slightly toward the chassis interior, engaging boss 106D formed in cassette holder 101 becomes engaged with slanting surface 123a of shutter 123 so as to forcibly move shutter 123 downward opposing the force of spring 124. As a result, opening 123b of shutter 123 moves into the optical path between light emitter 121 and light-receiving sensor 122 so that it allows light-receiving sensor 122 to receive the sensor light from light emitter 121. This activates an unillustrated motor whose driving force is transmitted to rack gear 119f. As a result, driving plate 119 moves toward the chassis interior to the position where abutment piece 119d abuts double-acting plate 118. Then, driving plate 119 and double-acting plate 118 move altogether toward the chassis interior.
The subsequent procedures of the loading operation as well as the ejecting operation of S-cassette SC are the same as those of L-cassette LC, therefore the description is omitted.
In the conventional cassette loading device 100 stated above, the point for staring the in-pulling operation of a cassette for loading L-cassette LC differs from that for loading S-cassette SC. This difference sometimes causes malfunctions or damage to the appliance. The following illustrates these phenomena.
In general, in a cassette loading device, the point for starting the in-pulling operation of a cassette is set up in the following manner. When the cassette is pushed in with the fingers to a position where the cassette loading switch is turned on, the cassette in-pulling operation is activated (the cassette loading switch is turned on so that an unillustrated driving motor starts to cause the driving plate 119 to perform pull-in action) if the cassette is pushed in to a predetermined position sd in order to prevent the fingers from being caught between the cassette inserting port and the cassette and injured. This predetermined position sd is typically set up in such a position that the rear end face of the cassette, with respect to the loading direction, is depressed toward the chassis interior by d (=0 to 10 mm) from the VTR front panel FP (see FIGS. 7B and 7D).
However, the two kinds, small and large types of cassettes LC and SC handled by cassette loading device 100 must be positioned so that the mouth positions of cassettes LC and SC after they have been loaded will coincide with each other. (Here, the mouth position means the reference position on the forward side in the loading direction of cassette LC or SC, which serves as the reference point for drawing out the magnetic tape.) As a result of this positioning, the rear ends, with respect to the loading direction, of the different types of cassettes are positioned with a difference D, as shown in FIG. 8, and it was impossible to avoid this.
In the conventional cassette loading device 100, the timing for the cassette in-pulling operation was set up so as to be suitable for S-cassette SC. Specifically, during the loading of an S-cassette SC, the cassette in-pulling operation is started when the rear side with respect to the cassette loading direction has reached the aforementioned predetermined position sd (see FIGS. 7B, 7D). In this case, however, during the loading of an L-cassette LC, the L-cassette LC starts to be pulled in when its rear side is located at a position ld (see FIGS. 6B and 6D), or at a distance of D' (=D-(0-10 mm)) from the VTR front panel FP. The projected amount of L-cassette LD (the distance projected from the VTR front panel) becomes too large.
For this reason, it structurally becomes possible for the user to hold the rear part of the L-cassette LC during the loading of the L-cassette LC, and draw it out or change the loading position of it despite the fact that cassette in-pulling operation has been already started. This means that the apparatus may perform the cassette in-pulling operation even with no cassette inserted, or the L-cassette LC may be displaced out of position back and forth relative to L-cassette guiding piece 104. This resulted in malfunctions and damage to the appliance.
When, during the insertion of cassette, each cassette LC and SC abuts stopper pieces 104a and 105a, the projected amounts of cassettes LC and SC from the VTR front panel FP differ, resulting in ineptness of cassette insertion and degrading the handling performance. Specifically, if the projected amount sD (see FIGS. 7A and 7C) of S-cassette SC from the VTR front panel FP when it abuts stopper piece 105a, is set optimally (at about 10 mm; this might change depending upon the size of the S-cassette SC and the aforementioned predetermined position sd), the projected amount 1D (see FIGS. 6A and 6C) of L-cassette LC from the VTR front panel FP when it abuts stopper piece 104a, becomes a large value, i.e., lD=sD+D. Consequently, the projected amounts sD and lD for both the cassettes SC and LC differ considerably. This results in ineptness of cassette insertion. Besides, during the operation, the operation with L-cassette LC projected out to such a large degree is awkward and clumsy looking, degrading the handling performance.